dog - O.E. docga, a late, rare word used of a powerful breed of canine. It forced out O.E. hund (the general Gmc. word) by 16c. and subsequently was picked up in many continental languages, but the origin remains one of the great mysteries of English etymology. Slang meaning "ugly woman" is from 1930s; that of "sexually aggressive man" is from 1950s. The verb meaning "to track like a dog" is from 1519. Doggerel is from 1277; dog tag is from 1918. Dog-gone (1851) is Amer.Eng., "fantastic perversion of god-damned" [Weekley]. Dogs "feet" is 1913, from rhyming slang dog's meat. To dog-ear a book is from 1659; dog-eared in extended sense of "worn, unkempt" is from 1894. Dogfight "aerial combat" is World War I air forces slang, from earlier meaning "riotous brawl" (1880s). Many expressions -- a dog's life (1607), go to the dogs (1864), etc. -- reflect earlier hard use of the animals as hunting accessories, not pampered pets. Dogfish is first recorded 1475; dogwood is 1617, earlier dog-tree (1548). Dog days (1538), from L. dies caniculares, from Gk. (the star was also known as kyon seirios) are around the time of the heliacal rising of Sirius, the Dog-star, noted as the hottest and most unwholesome time of the year; usually July 3 to Aug. 11, but variously calculated, depending on latitude and on whether the greater Dog-star (Sirius) or the lesser one (Procyon) is reckoned. The heliacal rising of Sirius has shifted down the calendar with the procession of the equinoxes; in ancient Egypt c.3000 B.C.E. it coincided with the summer solstice, which was also the new year and the beginning of the inundation of the Nile. The "dog" association apparently began here (the star's heiroglyph was a dog), but the reasons for it are obscure.